The tragic events of Sep. 11, 2001, and the anthrax exposure cases thereafter clearly demonstrated the risks of terrorist attacks on civilian populations anywhere in the world using weapons of mass destruction. Biological weapons pose a significant threat to such civilian populations. Although the anthrax exposure shortly after September 11 appears to be almost exclusively through contact with contaminated mail, these events highlight the potential risk from such biological agents. A likely mode of delivery of highly infectious or toxic agents is by atmospheric release since potentially large populations could be exposed in a relatively short time. Aerosol particles in the range of about 0.3 to about 15 microns in diameter could be delivered by rockets, bomblets with aerosol nozzles, missiles, aircraft equipped with tanks and spray nozzles (e.g., crop dusting aircraft, helicopters, and the like), small boats, trucks, or cars equipped with aerosol generators or from multiple fixed sites in a population-dense area. Delivery to sites 1 to 50 km upwind of large populations centers (e.g., the population corridor extending along the east coast from Washington, D.C., to Boston), could be devastating.
Aerosol or biological agents, if they enter the respiratory tract of a individual in sufficient amounts, present a high probability of an usually severe spectrum of the relevant disease and a very high mortality rate. To prevent wide spread casualties from an aerosol attack, it is imperative that access of aerosol particles (i.e., 1 to 5 microns) to the airway and conjunctivae of potential victims be markedly minimized.
Gas-type masks potentially offer protection from such aerosol bioattacks. To be effective, however, the masks must, in addition to filtering out or otherwise removing the biological agent, should be readily available, inexpensive, easy to use by essentially untrained personnel, present relatively small pressure gradients during breathing, easy to adapt to personnel of varying ages and/or sizes, lightweight, and comfortable to wear for prolonged periods of time (including periods of sleep). Unfortunately, currently available masks—generally of the military type—do not meet these requirements. Recently, U.S. Pat. No. 6,176,239 (Jan. 23, 2001), which is hereby incorporated by reference, provided an advanced chemical-biological mask. Although this mask represents a significant improvement relative to conventional military-type chemical-biological masks, it is expected to be too costly, complex, and uncomfortable for general civilian use in the case of a biological warfare attack. The present invention provides biological defense masks having the desired characteristics for general civilian population use.
Biological warfare aerosols are generally difficult to detect since they are usually invisible, odor-free, taste-free, and not detectable by condensation of liquid droplets. Thus, with only limited ability to detect a biological warfare aerosol attack, there is generally no signal to an at-risk population to implement the use of the biological defense masks (i.e., a mask-on signal). Likewise, in the event of an attack, there are no signals to indicate when it is safe to terminate the use of the biological defense masks (i.e., a mask-off signal). The present invention also provides methods, largely based on current and expected meteorological conditions downwind from, and within, the release area, to provide assistance in determining when and where to implement the use of the biological defense masks and when and where to terminate such use.